Infertility in Mares

July 2, 2007 (published)

Many of you may have mares that you would like to breed but have been unable to get them pregnant. If this is the case, you will probably need to be more aggressive to determine the cause of infertility rather than just trying to breed them again and see what happens. Most of these mares have problems that can be diagnosed by your veterinarian and then can either be treated or your vet may determine the problems are so severe the mare may never get pregnant. Although the basics of a reproductive exam should be performed, the first thing to consider is the overall health of the mare. Dr. Michelle Leblanc indicates that mares with other health problems, such as poor body condition, laminitis, or other painful conditions are not likely to get pregnant. Mares that have foundered generally have less mobility and this lack of mobility can cause them to accumulate fluid in the uterus, which decreases the chance of pregnancy. Also, if you have a mare that has foundered in the past, pregnancy can cause more problems due to the extra weight so I recommend these mares either not be bred or be used for embryo transfer only.

Another concern is stress. Mares that are not used to being with other mares, such as race mares, may have a difficult time getting pregnant while being with other mares. Nutrition can also play a role in breeding as mares in poor condition are unlikely to get pregnant. Some thin or old mares have poor conformation of the perineal area in which the anus is sunken and this predisposes the mare to infection. If you have an infertile mare, the money spent for a complete veterinary reproductive exam will save you time and money later.

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